Field of the Invention
The present disclosure relates to a touch sensor integrated type display device, and more particularly, to a touch sensor integrated type display device capable of improving image quality, uniformly distributing liquid crystals, and preventing a light leakage phenomenon.
Discussion of the Related Art
In recent years, flat panel displays (hereinafter abbreviated to “display devices”), which are able to be manufactured as a large-sized display device at a low price and have high display quality (including an implementation capability of a motion picture, a resolution, brightness, a contrast ratio, a color representation capability, etc.), are being developed in accordance with the need for the display devices capable of properly displaying the multimedia with the development of multimedia. Various input devices, such as a keyboard, a mouse, a track ball, a joystick, and a digitizer, have been used in the display devices to allow users to interface with the display devices.
However, when the user makes use of these input devices, user's dissatisfaction increases because the user is required to learn how to use the input devices and the input devices occupy space, thereby having difficulty in increasing the perfection of products. Thus, a demand for a convenient and simple input device for the display device capable of reducing erroneous operations is increasing. In response to the demand, a touch sensor was proposed to recognize information when the user inputs the information by directly touching the screen or approaching the screen with his or her hand or a pen while he or she watches the display device.
The touch sensor has a simple configuration capable of reducing the erroneous operations. The user can also perform an input action without using a separate input device and can quickly and easily manipulate a display device through the contents displayed on the screen. Thus, the touch sensor has been applied to various display devices.
The touch sensor used in the display device may be classified into an add-on type touch sensor, an on-cell type touch sensor, and an integrated type (or in-cell type) touch sensor depending on its structure. The add-on type touch sensor is configured such that the display device and a touch sensor module including the touch sensor are individually manufactured and then the touch sensor module is attached to an upper substrate of the display device. The on-cell type touch sensor is configured such that elements constituting the touch sensor are directly formed on the surface of an upper glass substrate of the display device. The integrated type touch sensor is configured such that elements constituting the touch sensor are mounted inside the display device to thereby achieve thin profile of the display device and increase the durability of the display device.
Among the above touch sensors, because the integrated type touch sensor may commonly use a common electrode of the display device as a touch electrode, a thickness of the display device may decreases as compared to the other touch sensors. Further, because the touch elements of the integrated type touch sensor are formed inside the display device, the durability of the display device may increase. Hence, the integrated type touch sensor has been widely used.
The integrated type touch sensor can solve the problems generated in the add-on type touch sensor and the on-cell type touch sensor because of the advantages of the thin profile and the durability improvement. The integrated type touch sensor may be divided into a light type touch sensor and a capacitive touch sensor depending on a method for sensing a touched portion. The capacitive touch sensor may be subdivided into a self capacitive touch sensor and a mutual capacitive touch sensor.
The self capacitive touch sensor forms a plurality of independent patterns in a touch area of a touch sensing panel and measures changes in a capacitance of each independent pattern, thereby deciding whether or not a touch operation is performed. The mutual capacitive touch sensor crosses X-axis electrode lines (for example, driving electrode lines) and Y-axis electrode lines (for example, sensing electrode lines) in a touch electrode formation area of a touch sensing panel to form a matrix, applies a driving pulse to the X-axis electrode lines, and senses changes in voltages generated in sensing nodes defined as crossings of the X-axis electrode lines and the Y-axis electrode lines through the Y-axis electrode lines, thereby deciding whether or not a touch operation is performed.
In the mutual capacitive touch sensor, a mutual capacitance generated in touch recognition of the mutual capacitive touch sensor is very small, but a parasitic capacitance between gate line and data lines constituting the display device is very large. Therefore, it is difficult to accurately recognize a touch position because of the parasitic capacitance.
Further, because a plurality of touch driving lines for a touch drive and a plurality of touch sensing lines for a touch sensing have to be formed on the common electrode for the multi-touch recognition of the mutual capacitive touch sensor, the mutual capacitive touch sensor requires a very complex line structure.
On the other hand, because the self capacitive touch sensor has a simpler line structure than the mutual capacitive touch sensor, touch accuracy may increase. Hence, the self capacitive touch sensor has been widely used, if necessary or desired.
A related art self capacitive touch sensor integrated type liquid crystal display (hereinafter referred to as “touch sensor integrated type display device”) is described below with reference to FIGS. 1 to 4. FIG. 1 is a plane view of a related art touch sensor integrated type display device. FIG. 2 is a plane view enlarging a partial area R1 shown in FIG. 1. FIG. 3 is a cross-sectional view taken along line I-I′ of FIG. 2. FIG. 4 is a waveform diagram showing a ripple generated in a common voltage due to a parasitic capacitance formed between a touch electrode (common electrode) and gate and data lines in the related art touch sensor integrated type display device.
As shown in FIG. 1, the related art touch sensor integrated type display device includes an active area AA, in which touch electrodes are formed and data is displayed, and a bezel area BA positioned outside the active area AA. In the bezel area BA, various wires and a source driving and touch sensing integrated circuit (IC) 10 are formed.
The active area AA includes a plurality of touch electrodes Tx11-Tx14, Tx21-Tx24, Tx31-Tx34, Tx41-Tx44, and Tx51-T54 divided in a first direction (for example, x-axis direction) and a second direction (for example, y-axis direction) crossing the first direction and a plurality of touch routing wires TW11-TW14, TW21-TW24, TW31-TW34, TW41-TW44, and TW51-TW54, which are respectively connected to the plurality of touch electrodes Tx11-Tx14, Tx21-Tx24, Tx31-Tx34, Tx41-Tx44, and Tx51-T54 and are arranged in parallel with one another in the second direction.
The plurality of touch electrodes Tx11-Tx14, Tx21-Tx24, Tx31-Tx34, Tx41-Tx44, and Tx51-T54 inside the active area AA are formed by dividing a common electrode of the display device, and thus operate as common electrodes in a display drive for displaying data and operate as touch electrodes in a touch drive for recognizing a touch position.
The bezel area BA positioned outside the active area AA includes the source driving and touch sensing IC 10 and various wires. In the display drive, a driving IC for the display device and the source driving and touch sensing IC 10 drive gate lines (not shown) of the display device, supply display data to data lines (not shown), and supply a common voltage to the touch electrodes (or the common electrodes). In the touch drive, the source driving and touch sensing IC 10 supplies a touch driving voltage to the touch electrodes and scans changes in a capacitance of each touch electrode before and after a touch operation, thereby determining a position of the touched touch electrode. The various wires include the touch routing wires TW11-TW14, TW21-TW24, TW31-TW34, TW41-TW44, and TW51-TW54 connected to the touch electrodes Tx11-Tx14, Tx21-Tx24, Tx31-Tx34, Tx41-Tx44, and Tx51-T54, the gate lines connected to the source driving and touch sensing IC 10, and the data lines.
As shown in FIGS. 2 and 3, the related art touch sensor integrated type display device includes a thin film transistor TFT formed on a substrate SUB, a pixel electrode Px connected to a drain electrode DE of the thin film transistor TFT, and the touch electrode Tx11 which overlaps the pixel electrode Px and forms a horizontal electric field.
The thin film transistor TFT includes a gate electrode GE extending from a gate line GL formed on the substrate SUB, a semiconductor active layer A which is formed on a gate insulating layer GI covering the gate line GL and the gate electrode GE and overlaps a portion of the gate electrode GE, and a source electrode SE and the drain electrode DE which are formed on the semiconductor active layer A and are separated from each other by a predetermined distance. A data line DL is formed on the same layer as the drain electrode DE.
The pixel electrode Px is formed on the gate insulating layer GI and the drain electrode DE and is directly connected to the drain electrode DE.
The data line DL, the source electrode SE and the drain electrode DE of the thin film transistor TFT, and the pixel electrode Px are covered with a first passivation layer PAS1. The touch routing wire TW11 is formed on the first passivation layer PAS1 and overlaps the data line DL. The touch routing wire TW11 on the first passivation layer PAS1 is covered with a second passivation layer PAS2.
The touch electrode Tx11 is formed on the second passivation layer PAS2. The touch electrode Tx11 has a plurality of slits SL, so as to form the horizontal electric field along with the pixel electrode Px formed on the gate insulating layer GI.
In the related art touch sensor integrated type display device having the above-described structure, when a finger or a conductive metal such as a stylus pen touches the active area AA of the display device, the touch sensor integrated type display device may sense changes in a capacitance of the touch electrode before and after the touch electrode close to a touch position is touched, and may determine the touch position. Namely, the touch sensor integrated type display device may apply a driving pulse to the touch electrodes Tx11-Tx14, Tx21-Tx24, Tx31-Tx34, Tx41-Tx44, and Tx51-T54 formed in the active area AA and then may sense changes in a self capacitance of each touch electrode before and after each of the touch electrodes Tx11-Tx14, Tx21-Tx24, Tx31-Tx34, Tx41-Tx44, and Tx51-T54 is touched, thereby determining the touch position.
However, as the size and a resolution of the related art touch sensor integrated type display device increase, a parasitic capacitance between the touch electrode (the common electrode) and the gate and data lines increases. As shown in FIG. 4, the parasitic capacitance generates a ripple in the common voltage and adversely affects an image displayed on the display device. A common voltage compensation circuit may be designed so as to prevent the ripple. However, in this instance, there were the problems, in which the size of the bezel area may increase, or a parasitic capacitance may be additionally generated by the design of the common voltage compensation circuit.
Further, in the related art touch sensor integrated type display device, a relatively large step coverage is generated between a non-formation area of the data lines and the touch routing wires and a formation area of the data lines and the touch routing wires because of a vertical stack structure of the data lines and the touch routing wires formed in the active area. Thus, there were the additional problems, in which a small amount of liquid crystals are distributed in an area corresponding to the formation area of the data lines and the touch routing wires, or a light leakage phenomenon may be generated by the step coverage.